/****************************************************************************
 *
 * Copyright 2017 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/****************************************************************************
 * lib/libc/pthread/pthread_rwlock.c
 *
 *   Copyright (C) 2017 Mark Schulte. All rights reserved.
 *   Author: Mark Schulte <mark@mjs.pw>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <tinyara/config.h>

#include <stdint.h>
#include <sys/types.h>
#include <pthread.h>
#include <errno.h>
#include <debug.h>

#include <tinyara/semaphore.h>

/****************************************************************************
 * Public Functions
 ****************************************************************************/

int pthread_rwlock_init(FAR pthread_rwlock_t *lock, FAR const pthread_rwlockattr_t *attr)
{
	int err;

	if (lock == NULL) {
		return EINVAL;
	}

	if (attr != NULL) {
		return ENOSYS;
	}

	lock->num_readers = 0;
	lock->num_writers = 0;
	lock->write_in_progress = false;

	err = pthread_cond_init(&lock->cv, NULL);
	if (err != 0) {
		return err;
	}

	err = pthread_mutex_init(&lock->lock, NULL);
	if (err != 0) {
		pthread_cond_destroy(&lock->cv);
		return err;
	}

	return err;
}

int pthread_rwlock_destroy(FAR pthread_rwlock_t *lock)
{
	int cond_err = pthread_cond_destroy(&lock->cv);
	int mutex_err = pthread_mutex_destroy(&lock->lock);

	if (mutex_err) {
		return mutex_err;
	}

	return cond_err;
}

int pthread_rwlock_unlock(FAR pthread_rwlock_t *rw_lock)
{
	int err;

	err = pthread_mutex_lock(&rw_lock->lock);
	if (err != 0) {
		return err;
	}

	if (rw_lock->num_readers > 0) {
		rw_lock->num_readers--;

		if (rw_lock->num_readers == 0) {
			err = pthread_cond_broadcast(&rw_lock->cv);
		}
	} else if (rw_lock->write_in_progress) {
		rw_lock->write_in_progress = false;

		err = pthread_cond_broadcast(&rw_lock->cv);
	} else {
		err = EINVAL;
	}

	pthread_mutex_unlock(&rw_lock->lock);
	return err;
}
